WCF服务远程调用Linq出现异常

     一直以来都在学习中，所以也没有什么好文章献给大家，这次小弟也是来提问的，Dudu觉得不合适可以从首页撤掉。不过本人认为让更多的人看到问题也是不错的。
  问题如下：
   建立了Book数据库，库中有三张表Orders，Products，Remarks。其中Orders的字段Oid是Products字段Poid的主键，意思是这两张表组成了主外键关系。Remarks是一张独立的表。利用Linq To SQL设计器生成了三张表的实体类。并将三个实体类暴露给客户端（[DataContract]）.代码如下：
  
  
  Orders类：
  
  Code
   1[Table(Name="dbo.orders")]
   2 [DataContract(Name = "Orders", Namespace = "http://www.lgx.OrderLinq")]
   3 public partial class order : INotifyPropertyChanging, INotifyPropertyChanged
   4 {
   5
   6 private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);
   7
   8 private int _oid;
   9
   10 private System.Nullable<decimal> _totalPrice;
   11
   12 private System.DateTime _odate;
   13
   14 private EntitySet<product> _products;
   15
   16 Extensibility Method Definitions#region Extensibility Method Definitions
   17 partial void OnLoaded();
   18 partial void OnValidate(System.Data.Linq.ChangeAction action);
   19 partial void OnCreated();
   20 partial void OnoidChanging(int value);
   21 partial void OnoidChanged();
   22 partial void OntotalPriceChanging(System.Nullable<decimal> value);
   23 partial void OntotalPriceChanged();
   24 partial void OnodateChanging(System.DateTime value);
   25 partial void OnodateChanged();
   26 #endregion
   27
   28 public order()
   29 {
   30 this._products = new EntitySet<product>(new Action<product>(this.attach_products), new Action<product>(this.detach_products));
   31 OnCreated();
   32 }
   33
   34 [Column(Storage="_oid", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
   35 [DataMember(Order=0)]
   36 public int oid
   37 {
   38 get
   39 {
   40 return this._oid;
   41 }
   42 set
   43 {
   44 if ((this._oid != value))
   45 {
   46 this.OnoidChanging(value);
   47 this.SendPropertyChanging();
   48 this._oid = value;
   49 this.SendPropertyChanged("oid");
   50 this.OnoidChanged();
   51 }
   52 }
   53 }
   54
   55 [Column(Storage="_totalPrice", DbType="Decimal(18,3)")]
   56 [DataMember(Order = 1)]
   57 public System.Nullable<decimal> totalPrice
   58 {
   59 get
   60 {
   61 return this._totalPrice;
   62 }
   63 set
   64 {
   65 if ((this._totalPrice != value))
   66 {
   67 this.OntotalPriceChanging(value);
   68 this.SendPropertyChanging();
   69 this._totalPrice = value;
   70 this.SendPropertyChanged("totalPrice");
   71 this.OntotalPriceChanged();
   72 }
   73 }
   74 }
   75
   76 [Column(Storage="_odate", DbType="DateTime NOT NULL")]
   77 [DataMember(Order = 2)]
   78 public System.DateTime odate
   79 {
   80 get
   81 {
   82 return this._odate;
   83 }
   84 set
   85 {
   86 if ((this._odate != value))
   87 {
   88 this.OnodateChanging(value);
   89 this.SendPropertyChanging();
   90 this._odate = value;
   91 this.SendPropertyChanged("odate");
   92 this.OnodateChanged();
   93 }
   94 }
   95 }
   96
   97 [Association(Name="order_product", Storage="_products", OtherKey="poid")]
   98 [DataMember(Order = 3)]
   99 public EntitySet<product> products
  100 {
  101 get
  102 {
  103 return this._products;
  104 }
  105 set
  106 {
  107 this._products.Assign(value);
  108 }
  109 }
  110
  111 public event PropertyChangingEventHandler PropertyChanging;
  112
  113 public event PropertyChangedEventHandler PropertyChanged;
  114
  115 protected virtual void SendPropertyChanging()
  116 {
  117 if ((this.PropertyChanging != null))
  118 {
  119 this.PropertyChanging(this, emptyChangingEventArgs);
  120 }
  121 }
  122
  123 protected virtual void SendPropertyChanged(String propertyName)
  124 {
  125 if ((this.PropertyChanged != null))
  126 {
  127 this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
  128 }
  129 }
  130
  131 private void attach_products(product entity)
  132 {
  133 this.SendPropertyChanging();
  134 entity.order = this;
  135 }
  136
  137 private void detach_products(product entity)
  138 {
  139 this.SendPropertyChanging();
  140 entity.order = null;
  141 }
  142 }
  Products类：
  
  
  Code
   1[Table(Name="dbo.products")]
   2 [DataContract(Name = "Products", Namespace = "http://www.lgx.OrderLinq")]
   3 public partial class product : INotifyPropertyChanging, INotifyPropertyChanged
   4 {
   5
   6 private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);
   7
   8 private int _pid;
   9
   10 private int _poid;
   11
   12 private string _pName;
   13
   14 private decimal _price;
   15
   16 private System.DateTime _pdate;
   17
   18 private EntityRef<order> _order;
   19
   20 Extensibility Method Definitions#region Extensibility Method Definitions
   21 partial void OnLoaded();
   22 partial void OnValidate(System.Data.Linq.ChangeAction action);
   23 partial void OnCreated();
   24 partial void OnpidChanging(int value);
   25 partial void OnpidChanged();
   26 partial void OnpoidChanging(int value);
   27 partial void OnpoidChanged();
   28 partial void OnpNameChanging(string value);
   29 partial void OnpNameChanged();
   30 partial void OnpriceChanging(decimal value);
   31 partial void OnpriceChanged();
   32 partial void OnpdateChanging(System.DateTime value);
   33 partial void OnpdateChanged();
   34 #endregion
   35
   36 public product()
   37 {
   38 this._order = default(EntityRef<order>);
   39 OnCreated();
   40 }
   41
   42 [Column(Storage="_pid", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
   43 [DataMember(Order=0)]
   44 public int pid
   45 {
   46 get
   47 {
   48 return this._pid;
   49 }
   50 set
   51 {
   52 if ((this._pid != value))
   53 {
   54 this.OnpidChanging(value);
   55 this.SendPropertyChanging();
   56 this._pid = value;
   57 this.SendPropertyChanged("pid");
   58 this.OnpidChanged();
   59 }
   60 }
   61 }
   62
   63 [Column(Storage="_poid", DbType="Int NOT NULL")]
   64 [DataMember(Order = 1)]
   65 public int poid
   66 {
   67 get
   68 {
   69 return this._poid;
   70 }
   71 set
   72 {
   73 if ((this._poid != value))
   74 {
   75 if (this._order.HasLoadedOrAssignedValue)
   76 {
   77 throw new System.Data.Linq.ForeignKeyReferenceAlreadyHasValueException();
   78 }
   79 this.OnpoidChanging(value);
   80 this.SendPropertyChanging();
   81 this._poid = value;
   82 this.SendPropertyChanged("poid");
   83 this.OnpoidChanged();
   84 }
   85 }
   86 }
   87
   88 [Column(Storage="_pName", DbType="VarChar(50) NOT NULL", CanBeNull=false)]
   89 [DataMember(Order = 2)]
   90 public string pName
   91 {
   92 get
   93 {
   94 return this._pName;
   95 }
   96 set
   97 {
   98 if ((this._pName != value))
   99 {
  100 this.OnpNameChanging(value);
  101 this.SendPropertyChanging();
  102 this._pName = value;
  103 this.SendPropertyChanged("pName");
  104 this.OnpNameChanged();
  105 }
  106 }
  107 }
  108
  109 [Column(Storage="_price", DbType="Decimal(18,2) NOT NULL")]
  110 [DataMember(Order = 3)]
  111 public decimal price
  112 {
  113 get
  114 {
  115 return this._price;
  116 }
  117 set
  118 {
  119 if ((this._price != value))
  120 {
  121 this.OnpriceChanging(value);
  122 this.SendPropertyChanging();
  123 this._price = value;
  124 this.SendPropertyChanged("price");
  125 this.OnpriceChanged();
  126 }
  127 }
  128 }
  129
  130 [Column(Storage="_pdate", DbType="DateTime NOT NULL")]
  131 [DataMember(Order = 4)]
  132 public System.DateTime pdate
  133 {
  134 get
  135 {
  136 return this._pdate;
  137 }
  138 set
  139 {
  140 if ((this._pdate != value))
  141 {
  142 this.OnpdateChanging(value);
  143 this.SendPropertyChanging();
  144 this._pdate = value;
  145 this.SendPropertyChanged("pdate");
  146 this.OnpdateChanged();
  147 }
  148 }
  149 }
  150
  151 [Association(Name="order_product", Storage="_order", ThisKey="poid", IsForeignKey=true)]
  152 [DataMember(Order = 5)]
  153 public order order
  154 {
  155 get
  156 {
  157 return this._order.Entity;
  158 }
  159 set
  160 {
  161 order previousValue = this._order.Entity;
  162 if (((previousValue != value)
  163 || (this._order.HasLoadedOrAssignedValue == false)))
  164 {
  165 this.SendPropertyChanging();
  166 if ((previousValue != null))
  167 {
  168 this._order.Entity = null;
  169 previousValue.products.Remove(this);
  170 }
  171 this._order.Entity = value;
  172 if ((value != null))
  173 {
  174 value.products.Add(this);
  175 this._poid = value.oid;
  176 }
  177 else
  178 {
  179 this._poid = default(int);
  180 }
  181 this.SendPropertyChanged("order");
  182 }
  183 }
  184 }
  185
  186 public event PropertyChangingEventHandler PropertyChanging;
  187
  188 public event PropertyChangedEventHandler PropertyChanged;
  189
  190 protected virtual void SendPropertyChanging()
  191 {
  192 if ((this.PropertyChanging != null))
  193 {
  194 this.PropertyChanging(this, emptyChangingEventArgs);
  195 }
  196 }
  197
  198 protected virtual void SendPropertyChanged(String propertyName)
  199 {
  200 if ((this.PropertyChanged != null))
  201 {
  202 this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
  203 }
  204 }
  205 }
  Remarks类：
  
  
  Code
   1[Table(Name="dbo.REMARK")]
   2 [DataContract(Name = "Remarks", Namespace = "http://www.lgx.OrderLinq")]
   3 public partial class REMARK : INotifyPropertyChanging, INotifyPropertyChanged
   4 {
   5
   6 private static PropertyChangingEventArgs emptyChangingEventArgs = new PropertyChangingEventArgs(String.Empty);
   7
   8 private int _RID;
   9
   10 private string _RNAME;
   11
   12 private int _RCID;
   13
   14 private string _RCONTENT;
   15
   16 private System.DateTime _RTIME;
   17
   18 Extensibility Method Definitions#region Extensibility Method Definitions
   19 partial void OnLoaded();
   20 partial void OnValidate(System.Data.Linq.ChangeAction action);
   21 partial void OnCreated();
   22 partial void OnRIDChanging(int value);
   23 partial void OnRIDChanged();
   24 partial void OnRNAMEChanging(string value);
   25 partial void OnRNAMEChanged();
   26 partial void OnRCIDChanging(int value);
   27 partial void OnRCIDChanged();
   28 partial void OnRCONTENTChanging(string value);
   29 partial void OnRCONTENTChanged();
   30 partial void OnRTIMEChanging(System.DateTime value);
   31 partial void OnRTIMEChanged();
   32 #endregion
   33
   34 public REMARK()
   35 {
   36 OnCreated();
   37 }
   38
   39 [Column(Storage="_RID", AutoSync=AutoSync.OnInsert, DbType="Int NOT NULL IDENTITY", IsPrimaryKey=true, IsDbGenerated=true)]
   40 [DataMember(Order=0)]
   41 public int RID
   42 {
   43 get
   44 {
   45 return this._RID;
   46 }
   47 set
   48 {
   49 if ((this._RID != value))
   50 {
   51 this.OnRIDChanging(value);
   52 this.SendPropertyChanging();
   53 this._RID = value;
   54 this.SendPropertyChanged("RID");
   55 this.OnRIDChanged();
   56 }
   57 }
   58 }
   59
   60 [Column(Storage="_RNAME", DbType="VarChar(50) NOT NULL", CanBeNull=false)]
   61 [DataMember(Order = 1)]
   62 public string RNAME
   63 {
   64 get
   65 {
   66 return this._RNAME;
   67 }
   68 set
   69 {
   70 if ((this._RNAME != value))
   71 {
   72 this.OnRNAMEChanging(value);
   73 this.SendPropertyChanging();
   74 this._RNAME = value;
   75 this.SendPropertyChanged("RNAME");
   76 this.OnRNAMEChanged();
   77 }
   78 }
   79 }
   80
   81 [Column(Storage="_RCID", DbType="Int NOT NULL")]
   82 [DataMember(Order = 2)]
   83 public int RCID
   84 {
   85 get
   86 {
   87 return this._RCID;
   88 }
   89 set
   90 {
   91 if ((this._RCID != value))
   92 {
   93 this.OnRCIDChanging(value);
   94 this.SendPropertyChanging();
   95 this._RCID = value;
   96 this.SendPropertyChanged("RCID");
   97 this.OnRCIDChanged();
   98 }
   99 }
  100 }
  101
  102 [Column(Storage="_RCONTENT", DbType="VarChar(200) NOT NULL", CanBeNull=false)]
  103 [DataMember(Order = 3)]
  104 public string RCONTENT
  105 {
  106 get
  107 {
  108 return this._RCONTENT;
  109 }
  110 set
  111 {
  112 if ((this._RCONTENT != value))
  113 {
  114 this.OnRCONTENTChanging(value);
  115 this.SendPropertyChanging();
  116 this._RCONTENT = value;
  117 this.SendPropertyChanged("RCONTENT");
  118 this.OnRCONTENTChanged();
  119 }
  120 }
  121 }
  122
  123 [Column(Storage="_RTIME", DbType="DateTime NOT NULL")]
  124 [DataMember(Order = 4)]
  125 public System.DateTime RTIME
  126 {
  127 get
  128 {
  129 return this._RTIME;
  130 }
  131 set
  132 {
  133 if ((this._RTIME != value))
  134 {
  135 this.OnRTIMEChanging(value);
  136 this.SendPropertyChanging();
  137 this._RTIME = value;
  138 this.SendPropertyChanged("RTIME");
  139 this.OnRTIMEChanged();
  140 }
  141 }
  142 }
  143
  144 public event PropertyChangingEventHandler PropertyChanging;
  145
  146 public event PropertyChangedEventHandler PropertyChanged;
  147
  148 protected virtual void SendPropertyChanging()
  149 {
  150 if ((this.PropertyChanging != null))
  151 {
  152 this.PropertyChanging(this, emptyChangingEventArgs);
  153 }
  154 }
  155
  156 protected virtual void SendPropertyChanged(String propertyName)
  157 {
  158 if ((this.PropertyChanged != null))
  159 {
  160 this.PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
  161 }
  162 }
  163 }
  
  
   其次，建立WCF服务
  
  
  Code
   1[ServiceContract(Name = "IOrderService_Contract", Namespace = "http://www.lgx.OrderService/IOrderService_Contract/", SessionMode = SessionMode.Required)]
   2
   3 public interface IOrderService
   4 {
   5 [OperationContract(Name = "SaveOrder_Contract", Action = "http://www.lgx.OrderService/IOrderService/SaveOrder_Contract/", ReplyAction = "http://www.lgx.OrderService/IOrderService/SaveOrder_ContractResponse")]
   6 [ServiceKnownType(typeof(OrderLinq.product))]
   7 void SaveOrder(OrderLinq.order ord);
   8 [OperationContract(Name = "GetEnt_Contract", Action = "http://www.lgx.OrderService/IOrderService/GetEnt_Contract/", ReplyAction = "http://www.lgx.OrderService/IOrderService/GetEnt_ContractResponse")]
   9 Ent GetEnt();
  10 [OperationContract(Name = "GetOrder_Contract", Action = "http://www.lgx.OrderService/IOrderService/GetOrder_Contract/", ReplyAction = "http://www.lgx.OrderService/IOrderService/GetOrder_ContractResponse")]
  11 OrderLinq.order GetOrder();
  12
  13 [OperationContract(Name = "GetProduct_Contract", Action = "http://www.lgx.OrderService/IOrderService/GetProduct_Contract/", ReplyAction = "http://www.lgx.OrderService/IOrderService/GetProduct_ContractResponse")]
  14 product GetProduct();
  15
  16 [OperationContract(Name = "SaveRemak_Contract", Action = "http://www.lgx.OrderService/IOrderService/SaveRemak_Contract/", ReplyAction = "http://www.lgx.OrderService/IOrderService/SaveRemak_ContractResponse")]
  17 void SaveRemak(REMARK remark);
  18
  19 }
  
  
  
  建立客户端并进行远程引用和调用：
  
  
  
  
  Code
   1static void Main(string[] args)
   2 {
   3 //初始化属性
   4 Remarks remark = new Remarks();
   5 remark.RCID = 1;
   6 remark.RCONTENT = "顶一下";
   7 remark.RNAME = "五哥";
   8 remark.RTIME = DateTime.Now;
   9
  10 //初始化属性
  11 Orders orders = new Orders();
  12 orders.odate = DateTime.Now;
  13 orders.totalPrice = Convert.ToDecimal(0.0f);
  14
  15
  16 OrderService_ContractClient clients = new OrderService_ContractClient();
  17 //在这里操作评论表插入数据没有问题
  18 clients.SaveRemak_Contract(remark);
  19 //插入订单时提示EntitySet<product>为空，因为有主外键关系映射
  20 clients.SaveOrder_Contract(orders);
  21
  
   异常
  
  Code
   1
   2//这里提示EntitySet<product>为空，不知为何，
   3//如果数据库表没有主外键映射则不会有这个问题
   4//希望大家帮忙解决，实在是感激不尽呀！！
   5[Association(Name="order_product", Storage="_products", OtherKey="poid")]
   6 [DataMember(Order = 3)]
   7 public EntitySet<product> products
   8 {
   9 get
  10 {
  11 return this._products;
  12 }
  13 set
  14 {
  15 this._products.Assign(value);
  16 }
  17 }